A connectivity portfolio effect stabilizes marine reserve performance

Significance Networks of no-take marine reserves support local fisheries by ensuring a consistent supply of juvenile fish. We measured larval dispersal patterns for a highly exploited coral grouper and quantified temporal fluctuations in the recruitment contribution from a network of no-take marine reserves on the Great Barrier Reef. Although recruitment contributions from individual reserves are extremely variable, the reserve network generates a connectivity portfolio effect that successfully dampens the volatility of larval supply to nearby coral reefs. Our findings demonstrate that effective reserve networks can yield previously unrecognized stabilizing benefits that ensure a consistent replenishment of exploited fish stocks.